Note that a "bag of food" purchased at the airport (or even at, say Subway on your way to the airport) is very different from any size cooler of food. RMAMom is correct - 'disposable' food doesn't, or shouldn't, count as a carry-on item.
Your pocketbook DOES count at one of your allowed items. Reasonably, why wouldn't it? A movie camera carried in either its own individual case or by itself can reasonably be expected to count toward one's carry-on allowance, since it's being carried onto the plane separate from one's other item.